It is known that the handling of objects in industrial, logistics, and automated vending fields is generally managed by computerised systems for receiving/storing and retrieving/dispensing (ASR—automatic storage and retrieval) systems which, among other things, comprise robotic units for handling objects.
In large or medium-sized systems these units can be mounted on self-propelled bases; in small-sized systems they can be made mobile by means of arms which are controlled throughout different degrees of freedom, or other known controlled movement modalities. Various types of automatic dispenser designed for vending and renting objects of generally small dimensions (pharmaceuticals, snacks, video cassettes, DVDs and the like) belong to the category of ASR systems for small-sized objects.
There are two main known techniques for moving and piloting robotic units for handling and conveying, which are mounted on self-propelled bases. The first consists of making the units follow predetermined trajectories which a processor controlling the unit recognises by means of suitable sensors that are capable of detecting a signal produced by a guide arranged on the floor, or embedded in it. The signal can for example be of an optical type, and in this case the guide consists of a line obtained with particularly reflective paint; or of an electric type, in which case the corresponding guide consists of a conducting cable embedded in the floor, or of a strip of conductive material arranged on the floor surface.
The bases are provided with drive wheels and stabiliser devices. Operation of the drive wheels is in general precisely controllable by the unit processor, which can command synchronous rotation to obtain rectilinear motion, differentiated motion to achieve curved trajectories, or, if required, counter-rotation to enable the unit to rotate about its own vertical axis. Position stabilisers are usually constituted by pivoting, and possibly shock-absorbing, wheels.
Controlling these robotic units is a particularly complex and expensive task to achieve, and their positioning may possibly not be sufficiently precise when objects of very small dimensions must be identified, handled and repositioned.
Another known technique for piloting robotic handling and conveying units makes use of predetermined trajectories constituted by tracks which are constrained to the floor. In this case, the base of the unit is guided by the tracks and control over movements is limited to adjusting the speed and defining the direction of the movement.
Units of this type are however obliged to follow the trajectories defined by the tracks. Access to storage locations which are arranged facing each other requires the handling organs to be capable of operating on either side of the locations, for example using telescopic small forks or belts, or at least to be provided with a rotating base, capable of orienting the handling organs relative to the direction of the tracks. All of the aforesaid entails a high level of complexity for the mechanical organs of the robotic unit, with a consequent increase in production costs. Further, to obtain changes of direction of the robotic unit, curved guide elements having a curve radius of 3-4 meters may be used. This also increases the space which cannot be used for storing the objects.
The aim of this invention is to provide a system for moving and stabilising a mobile base of a robotic unit which enables the unit to move easily in the corridors between the shelving, to rotate around itself and also to move between different branches of the storage structure.
A further aim of the invention is to provide a system for moving and stabilising, which enables complex and modular storage structures to be constructed.
A further aim of the invention is to stabilise the robotic unit effectively when it has to stop in order to perform precise operations for recognising spaces or objects, and for handling the objects.
A still further aim of the invention is to provide a system for moving and stabilising which enables various robotic units to coexist in the same storage structure.